The present invention relates to a method of manufacturing a semiconductor integrated circuit device and more specifically to a semiconductor integrated circuit device manufacturing method having a process of forming a trench isolation.
The trench isolation is an element isolating part in a semiconductor substrate, which electrically isolates adjoining semiconductor integrated circuit elements by filling a groove formed between adjacent semiconductor integrated circuit elements with a specified burying material.
An example method of forming trench isolation examined by the inventor of this invention will be described below. After a groove is formed in a semiconductor substrate, an insulating film is formed on the inner surface of the groove. Then, a polycrystalline silicon film is deposited on the semiconductor substrate, after which the polysilicon film is etched back to fill only the groove with the polysilicon. After this, the semiconductor substrate is oxidized to oxidize the upper part of the polysilicon film in the groove, thus transforming the upper part into an insulating film.
An example method of burying an insulating film in the groove is disclosed in Japanese Patent Laid-Open No.143548/1983. The outline of this method is as follows. First, a side wall of an insulating film is formed on the inner wall surface of the groove to form a tapered surface on the inner wall surface of the groove, after which a burying insulating film is deposited over the semiconductor substrate. Next, the burying insulating film is etched back to bury the insulating film only in the groove.